In the book Your Inner Fish, by Neil Shubin presents the concept of evolution and how we can trace the parts that make up the human body to jellyfish, worms and even fish . The book not only discusses how we became who we are today, but also the implications our ancestors had on our current body pattern. In this essay I will demonstrate that I have digested Shubin's entire book by convincing you (dear reader) that everything in our body is based on simple modifications to already existing systems. To make this case, I will use evidence of limb development in a wide range of organisms, the four arches found in the embryological stage of development, the structures inside our noses, and the way our ears formed due of changes. There's a pattern common to all limbs: one bone, followed by two bones, then a bunch of little bones, and finally the fingers. This set of bones is present in many species including, but not limited to, bats, whales, and lizards. But how do these limbs develop and why do they all look similar? Shubin explains this by conveying that there are certain genetic switches that help piece together who we are. When scientists went looking for this genetic switch in the limbs, they found a couple of areas of tissue in the limbs that allow this body plan to occur. “A strip of tissue at the end of the limb bud is essential for the development of the entire limb… This patch of tissue has been called the zone of polarizing activity (ZPA).” ZPA allows humans to have opposable thumbs and little fingers. In other organisms, it differentiates the “thumb” side from the “little finger” side. Scientists then wanted to discover the molecule that allowed this change in the ZPA, the answer is Sonic hedgehog. Shubin points out that every animal with limbs h...... center of paper ......restful is that we also share the Pax 2 gene which is active in the ear region and starts a chain reaction of genetic activity that leads to the development of the inner ear. This common gene shows evidence of a common history and how our bodies are made up of many modifications. Neil Shubin's book is very informative about how our inner fish is real and definitely present in our bodies today. I have provided evidence to support how our bodies rely on simple changes (relatively) to already existing systems. This is also seen today when scientists study organisms with a simpler body structure than ours to understand medical conditions and mutations in the human body. We were created by variations and modifications to become what we are today and that is an amazing thing. Our bodily design was possible thanks to simpler organisms and this gave rise to the life we ​​know today.